MAX‐DOAS measurements of BrO and NO<sub>2</sub> in the marine boundary layer

Leser, H. G.; Hönninger, G.; Platt, U.

doi:10.1029/2002gl015811

Cited by 154 publications

(194 citation statements)

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“…18−20 In May−June 2007, an intensive field campaign (RHaMBLe, Reactive Halogens in the Marine Boundary Layer) took place at CVAO and in the Cape Verde region, onboard the UK Dornier 228 research aircraft and the UK research vessel RRS Discovery. 20 Additionally, five research cruises traversed the Cape Verde region: two of the R/V Polarstern (October 2000 5 The results of the BASE and IOD model cases were compared to the published measurements of halogen species from CVAO and the research cruises (Table S2): since the measurements were made in different years/seasons and in different places (although in the same region), we only considered the range of the observed values, divided into "clean" and "semipolluted" conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Sommariva

Glasow

2012

Environ. Sci. Technol.

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We used a one-dimensional model to simulate the chemical evolution of air masses in the tropical Atlantic Ocean, with a focus on halogen chemistry. The model results were compared to the observations of inorganic halogen species made in this region. The model could largely reproduce the measurements of most chlorine species, especially under unpolluted conditions, but overestimated sea salt chloride, BrCl, and bromine species. Agreement with the measurements could be improved by taking into account the reactivity with aldehydes and the effects of dimethyl sulfide (DMS) and Saharan dust on aerosol pH; a hypothetical HOX → X − aqueous-phase reaction could also improve the agreement with measured Cl 2 and HOCl, especially under semipolluted conditions. The results also showed that halogens speciation and concentrations are very sensitive to cloud processing. The model was used to calculate the impact of the observed levels of halogens: Cl atoms accounted for 5.4−11.6% of total methane sinks and halogens (mostly bromine and iodine) accounted for 35−40% of total ozone destruction. ■ INTRODUCTIONThe tropical marine boundary layer (MBL) is a region of particular interest for atmospheric chemistry: high levels of solar radiation, along with high temperatures and relative humidities, result in a highly oxidizing environment. It is estimated that the tropical atmosphere accounts for up to 80% of the global oxidation of methane (the second most important greenhouse gas) and that ∼25% of the global oxidation of methane occurs in the tropical MBL. 1 Halogen species (chlorine, bromine, iodine) are known to play an important role in the chemical processes of the MBL, particularly with regard to the nitrogen and ozone cycles, sulfur chemistry and particle formation: an overview of halogen chemistry and its impact on atmospheric chemical processes can be found in ref 2. Measurements of these species in the tropical region are sparse, but a number of recent studies 3−13 have reported observations of several halogen species in the tropical Atlantic Ocean. These studies suggested that halogen chemistry is responsible for a large fraction (∼30%) of ozone destruction in the Tropics 6 and up to 7% of the global methane destruction. 9 In this paper, we used the one-dimensional chemical model MISTRA to study halogen chemistry in the tropical Atlantic Ocean and the evolution of the chemical composition of air masses traveling across the ocean to the islands of Cape Verde, 900 km West of the coast of Africa. We compared the model results to the database of published observations of halogen species from this region with the objective of testing our understanding of halogen chemistry and of quantifying the impact of the observed halogens levels on ozone (O 3 ) and methane (CH 4 ). ■ METHODSModel. MISTRA is a one-dimensional model of the MBL. The model includes a description of meteorological and microphysical processes in the MBL and is described in detail in refs 14 and 15. Version 7.4.1 of MISTRA includes a number of improvement...

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Section: ■ Introductionmentioning

confidence: 99%

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Sommariva

Glasow

2012

Environ. Sci. Technol.

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“…von Glasow and Crutzen (2003) for an overview). BrO has been found in the boundary layer during polar ozone depletion events (ODEs) (Hausmann and Platt, 1994), over salt lakes Stutz et al, 2002;Hönninger et al, 2004), and in the marine boundary layer (MBL) (Leser et al, 2003;Saiz-Lopez et al, 2004) and also in volcanic plumes (Bobrowski et al (2003), N. Bobrowski, pers. comm.).…”

Section: Introductionmentioning

confidence: 99%

Impact of reactive bromine chemistry in the troposphere

et al. 2004

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Abstract.Recently several field campaigns and satellite observations have found strong indications for the presence of bromine oxide (BrO) in the free troposphere. Using a global atmospheric chemistry transport model we show that BrO mixing ratios of a few tenths to 2 pmol mol −1 lead to a reduction in the zonal mean O 3 mixing ratio of up to 18% in widespread areas and regionally up to 40% compared to a model run without bromine chemistry. A lower limit approach for the marine boundary layer, that does not explicitly include the release of halogens from sea salt aerosol, shows that for dimethyl sulfide (DMS) the effect is even larger, with up to 60% reduction of its tropospheric column. This is accompanied by dramatic changes in DMS oxidation pathways, reducing its cooling effect on climate. In addition there are changes in the HO 2 : OH ratio that also affect NO x and PAN. These results imply that potentially significant strong sinks for O 3 and DMS have so far been ignored in many studies of the chemistry of the troposphere.

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“…The model framework includes gas-aerosol partitioning of semi-volatile organic compounds (Liao et al, 2007;Henze et al, 2007Henze et al, , 2009Fu et al, 2008;Heald et al, 2011;Wang et al, 2011), and heterogeneous chemistry (Jacob, 2000). Coupling between gas-phase chemistry and sulfateammonium-nitrate aerosol is described by Park et al (2004) and Pye et al (2009).…”

Section: Global Modelmentioning

confidence: 99%

“…Observations of BrO and IO radicals within the MBL have demonstrated widespread impacts on atmospheric composition and chemistry (Alicke et al, 1999;Sander et al, 2003;Leser et al, 2003;Saiz-Lopez and Plane, 2004;SaizLopez et al, 2004SaizLopez et al, , 2006Peters et al, 2005;Whalley et al, 2007;Mahajan et al, 2010a;Commane et al, 2011;Dix et al, 2013;Gomez Martin et al, 2013;Le Breton et al, 2017), including significant effects on HO x concentrations and on the HO 2 : OH ratio in coastal and marine locations (Bloss et al, 2005a(Bloss et al, , 2010Sommariva et al, 2006;Kanaya et al, 2007;Whalley et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Impacts of bromine and iodine chemistry on tropospheric OH and HO<sub>2</sub>: comparing observations with box and global model perspectives

et al. 2018

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Abstract. The chemistry of the halogen species bromine and iodine has a range of impacts on tropospheric composition, and can affect oxidising capacity in a number of ways. However, recent studies disagree on the overall sign of the impacts of halogens on the oxidising capacity of the troposphere. We present simulations of OH and HO 2 radicals for comparison with observations made in the remote tropical ocean boundary layer during the Seasonal Oxidant Study at the Cape Verde Atmospheric Observatory in 2009. We use both a constrained box model, using detailed chemistry derived from the Master Chemical Mechanism (v3.2), and the three-dimensional global chemistry transport model GEOSChem. Both model approaches reproduce the diurnal trends in OH and HO 2 . Absolute observed concentrations are well reproduced by the box model but are overpredicted by the global model, potentially owing to incomplete consideration of oceanic sourced radical sinks. The two models, however, differ in the impacts of halogen chemistry. In the box model, halogen chemistry acts to increase OH concentrations (by 9.8 % at midday at the Cape Verde Atmospheric Observatory), while the global model exhibits a small increase in OH at the Cape Verde Atmospheric Observatory (by 0.6 % at midday) but overall shows a decrease in the global annual mass-weighted mean OH of 4.5 %. These differences reflect the variety of timescales through which the halogens impact the chemical system. On short timescales, photolysis of HOBr and HOI, produced by reactions of HO 2 with BrO and IO, respectively, increases the OH concentration. On longer timescales, halogen-catalysed ozone destruction cycles lead to lower primary production of OH radicals through ozone photolysis, and thus to lower OH concentrations. The global model includes more of the longer timescale responses than the constrained box model, and overall the global impact of the longer timescale response (reduced primary production due to lower O 3 concentrations) overwhelms the shorter timescale response (enhanced cycling from HO 2 to OH), and thus the global OH concentration decreases. The Earth system contains many such responses on a large range of timescales. This work highlights the care that needs to be taken to understand the full impact of any one process on the system as a whole.

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MAX‐DOAS measurements of BrO and NO₂ in the marine boundary layer

Cited by 154 publications

References 16 publications

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Impact of reactive bromine chemistry in the troposphere

Impacts of bromine and iodine chemistry on tropospheric OH and HO<sub>2</sub>: comparing observations with box and global model perspectives

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MAX‐DOAS measurements of BrO and NO2 in the marine boundary layer

Cited by 154 publications

References 16 publications

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

Impact of reactive bromine chemistry in the troposphere

Impacts of bromine and iodine chemistry on tropospheric OH and HO&lt;sub&gt;2&lt;/sub&gt;: comparing observations with box and global model perspectives

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MAX‐DOAS measurements of BrO and NO₂ in the marine boundary layer

Impacts of bromine and iodine chemistry on tropospheric OH and HO<sub>2</sub>: comparing observations with box and global model perspectives